Column of a material maker (18)
Published 27 September 2016 by Caroline Grellier
Our material maker flew off to Africa to recharge the batteries and get her fill of Togolese, Burkinabe and Beninese inspiration for Termatière, fabrication of bio-sourced materials project.
I am lucky: I am passionate about my job, I work without realizing. So, idle holidays, crayfish style laying by the pool, not for me! But since it is also necessary to switch off from vine shoots, I set off towards African horizons.
Objective: recharge the batteries and satisfy my insatiable curiosity for this DIY African culture that inspires me so much. And between two coconuts, I was also counting on working on some fabrication of local materials ideas, to take out of the box later.
Earth + ? = lasting brick
And in my box, a topic is seriously tantalizing me: finding an alternative to cement in the stabilization of terra cotta. I actually strongly believe in the future of these bricks, given the urgency regarding the sustainable construction needs on the African continent with an overwhelming urbanization rate. But cement, even added in small proportion to the earth (between 6 and 11%) wreaks havoc, as discussed at length at the 2016 Terra Congress in Lyon, starting with the disappearance of one of the main advantages of the earthen material: its recyclability.
But each problem has its solution and according to me, many solutions are to be found in our local and agricultural resources. I therefore looked into the issue by applying my creativity. And to find inspiration, I started by immersing myself in documents relating natural ancestral African recipes dedicated to construction. I came across plenty of African traditional methods using cow patty, straw, rice bran, to reinforce sealants in earthen constructions. No need indeed to reinvent the wheel, but rather to examine how a “village” technique can be developed and modernized to aim to meet a certain productivity injunction the bricks will require.
Gathering of agricultural waste expedition in Assahoun
In order to take action, I offered the Lome Construction and accommodation center (CCL) in Togo to participate with me in the prototyping of these famous bricks. I wanted to test the potential of a decoction of banana tree trunks and leaves (ancestral Ghanaian recipe used for sealants but not as an additive in bricks) and a decoction of fibers of palm nut husks and the residue of pressed palm oil.
Off to Assahoun, small town 50 km from Lome, on the search for banana plantations and palm groves. After several swift negotiations in the local language with the owner, the banana tree trunk that had already given bananas fell under the strokes of the machete.
And two hours later, following a detailed visit of the transformation unit Ave Palm, we returned with bags and buckets full of waste (more or less odorous). Let’s get to work!
The following day at the CCL, equipped with knives, a portable stove, a cooking pot, we prepared a decoction of banana tree residues, following the Ghanaian recipe to the letter: cut the stems and leaves into pieces and let them boil until you obtain slimy water.
The first attempt didn’t really work. Second attempt with the trunk, a part that contains more sap. Not great either, the water did not change consistence. For the third attempt, we left the stems, leaves and trunks to macerate in water for a week before boiling the juice. No conclusive result either. Therefore, to be tested and retested again!
With the palm tree oil, the bricks were easily made with the help from mason craftsmen from the CCL.
And just by weighing them up, I already noticed that the bricks with fibers of palm nut husks were lighter and also more solid than bricks with cement. But with the residue of pressed palm oil, a downright unpleasant small exuded from the brick…Hence, trails to follow with these small fibers…
Potemat, a Beninese curiosity
During my travels, I made a detour via the Beninese capital, Cotonou, at the university of Abomey-Calavi. I met there Chakirou Akanho Toukourou, initiator of the Potemat laboratory (Technological center for the promotion of local materials) at the “école polytechnique d’Abomey-Calavi” (Epac) – Institute of Technology.
This enthusiast and creative person at heart explained to me for more than three hours the ongoing research: tiles made from acacia gum, earthen bricks reinforced with strands of nylon hair, composite panels made from coconut fibers, etc.
The African actors of research in local materials, even though active, are still not very visible. Discovering that they were, like me, convinced that the materials of tomorrow will be bio-sourced enhances my imagination for future collaborations with Termatière…